Air compressor



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AIR COMPRESSOR 2 Sheets-Sheet 1 Filed March 16, 1965 INVENTORS CURTISPV. HU YSER 7. l/AAS JR.

FREDERICK NQ @N ATTORNEY sept- 6, 1966 c. w. HUYSER ETAL 3,270,955

AIR COMPRESSOR Filed March 16, 1965 g Sheets-Sheet 3 CU T/S FREDERICK will r 14. Q QQ NM QV vm w QM lllgwilwl I. mm @v mm 9w .l! w S 4 m 1.. mmQQ W Nu l mu Mw wk EL Q m Q QN NN United States Patent 3,270,955 AIRCOMPRESSOR Curtis W. Huyser, Zeeland, and Frederick T. Vaas, Jr.,

Grand Rapids, Mich., assignors to General Motors Corporation, Detroit,Mich., a corporation of Delaware Filed Mar. 16, 1965, Ser. No. 440,130Claims. (Cl. 230232) This invention relates to air compressors and moreparticularly to air compressors of the positive displacement rotaryimpeller type.

In various pressurized air systems it is desirable to include an aircompressor that operates quietly. Such systems, for example, areincorporated on motor vehicles to provide a source of pressure forsuper-charging, antismog control devices, air suspension systems or thelike and the proximity of the compressor unit in the system to thepassenger car compartment is such that the compressor should operatewithout unnecessarily increasing the general level of noise transmittedinto the passenger compartment. Compressed air systems might also beused in household heating systems located closely adjacent livingquarters, in which case, the level of noise from the compressor unit isalso an important consideration.

One particular type of compressor is especially suitable from a coststandpoint. This type of compressor can be characterized as a positivedisplacement rotary compressor having a rotor operable within a cavityto produce air compression. In such compressors there are two primarysources of noise that can be undesirable. Namely, the rotation of therotor within the pumping cavity can cause physical impacting noises,especially in the case of low-cost units having minimum bearing supportfor the drive shaft and rotor. Also, the variable volume pumpingcharacteristics of such compressors can cause a noticeable and, in somecases, undesirable pulsating noise attributable to the flow of fluidinto and out 9f the cavity. 1

It is an object of the present invention, therefore, to improve low-costrotary compressors for association with compressed auxiliary air systemsby silencing operating noises in the compressor by the provision of acompressor housing end cover plate having inlet and outlet openingstherein associated with a large volume mufiling cavity serving as ahousing for a large surface area filtering element and wherein the fluidflow through the mufiling cavity is directed through an elongatedtubular inlet member which, in cooperation with the large volumemuffling cavity, reduces fluid flow noise.

A further object of the present invention is to 'improve low-cost aircompressors of the rotary positive displacement type by silencingoperating noises in the compressor by the provision of a compact outerhousing cover plate with an extension thereon forming a large volumecavity for receiving a large surface area filter member where the largevolume cavity of the extension is closed by an end plate forming incooperation with the extension a continuous annular inlet opening to thelarge volume cavity; wherein the large volume cavity and end platecombine to muflle mechanical noises generated during the compressingoperation; and wherein an elongated tubular intake member within thefiltering element cooperates with the large volume cavity to effectivelymufiie pulsating fluid flow producednoises in the structure.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

3,270,955 Patented Sept. 6, 1966 ice In the drawings:

FIGURE 1 is an end elevational view, partially broken away, of thecompressor of the present invention;

FIGURE 2 is a view in vertical section taken along the line -2--2 ofFIGURE 1; and

FIGURE 3 is a view in vertical section taken along the line 3-3 ofFIGURE 1.

Referring to the drawings, in FIGURES 1 and 2, a compressor 10 is shownassociated with an electric drive motor 12 having a 'U-shaped bracket 14thereon for mounting the combination motor-compressor assembly withrespect to an associated system, for example, a fuel supply system for agas turbine requiring compressed aspiration air for directing fuel intothe combustion chamber of the turbine.

The compressor 10, more particularly, includes a base plate 16 havingintegrally formed cooling fins 18 thereon directed radially outwardlyfrom the outer periphery thereof. On one end of the base plate 16 islocated a radially outwardly directed flange 20 secured to the hOllS-rging of the motor 12 by suitable means such as tie bolts 22 for securingthe compressor 10 to the motor 12. On the opposite end of the base plate16 is located a cylinder 24 having a plurality of cooling fins 26 on theouter periphery thereof and including an interiorly located compressingcavity 28. In this embodiment of the invention the cylinder 24 issecured to the base plate 16 by a plurality of screws 30 whereby oneopened end of the cylinder 24 is closed by an end wall 32 of the baseplate 16. A recess 34 in the wall 32 receives a bearing assembly 36through which is directed a rotatable shaft 38 from the motor .12 andinteriorly of the pumping cavity 28. The bearing 36 is held in therecess 34 to rotatably support the shaft 38 by a bearing retainer plate40 secured on the inner surface of the end wall 32 to overlie the recess34.

On the opposite end of the cylinder 24 is located a cover plate 42having an end wall 44 serving to close the opposite open end of thecylinder 24. Tie bolts 45 connect the plate 42 and cylinder 24. The endwall 44 includes a centrally located recess 46 therein whichsupportingly receives the terminal end of the shaft 38 for guidedrotation within the cavity 28. One characteristic of the compressor 10is that the bearing support for the shaft 38 is relatively inexpensiverequiring only a common roller bearing assembly 36 and the recess 46 inthe end wall 44 of the cover plate 42.

Secured to the portion of the shaft 38 located within the cavity 28 is arotor member 48 fixedly secured to the shaft by set screws 50 inengagement with a .flat 52 on one side of the shaft 38. The rotor 48 hasa plurality of radially directed grooves 54 therein supporting radiallyoutwardly directed vane members 56 for relative reciprocation withrespect thereto. To reduce the cost of the unit, the vanes 56 duringoperation of the device have the ends thereof held in fluid sealingengagement with the inner surface of the cylinder 24 by centrifugalforce. The compressing cavity 28 is eccentrically disposed with respectto the shaft 38 and the rotor 48 and vane elements 56 divide it intoinlet cavities 5-8, 60 and discharge cavities 62, 64, as best .seen inFIGURE 3. Formed on the end wall 44 of the cover plate 42 is an inletopening 66 which communicates with the intake cavity 60 and with theintake-cavity 58 through an areuate groove 68 in the wall 44intercommunicating the chambers 58, 60. The wall 44 also includes anoutlet opening 70 communicated with the discharge cavities 62, 64through an arenate groove 72 in the end plate.

As best seen in FIGURE 2, the outlet 70 communicates through apassageway 74 in the wall 44 directed exteriorly of the cover plate 4 2through the outer periphery thereof. The inlet opening 66 communicateswith an elongated tubular intake snout 76 shown as being integrallyformed with the end wall 44 and directed therefrom exteriorly of thecavity 28. By virtue of this arrangement, upon rotation of the rotor 48in the cavity 28, the vanes 56 sweep across the intake groove 68 to drawfluid through the snout 76 and opening 66 int-o the variable volumeintake chambers 58, 60. Because of the eccentric arrangement of thepumping cavity 28 with respect to the rotor 48, the fluid is compressedin the discharge chambers 62,164 to be discharged across the groove 72thence through the outlet opening 70.

As indicated above, the compressor is characterized by a relativelyinexpensive bearing and rotor-vane arrangement. Such units are verydesirable from a cost standpoint, but they do have substantial playbetween the relatively movable parts. Thus, there is a tendency forimpacting of relatively moving parts with respect to one another with aconsequent undesirable noise emanation from the compressor unit 10.Moreover, because of the pumping characteristics of rotary pumps of theabovedescribed type, a pulsating fluid flow pattern is present that canproduced an undesirable fluid flow noise emission from the compressor10.

In accordance with certain principles of the present invention,therefore, the cover plate 42 includes features for substantiallyreducing the mechanical and fluid noises produced in compressors of thistype. The features are characterized by the fact that they can beincorporated in the relatively compact low-cost compressor structureWithout materially changing the lowcost of the compressor and,furthermore, the noise mufi'ling features also enable a highlyefliective air filtering arrangement to be incorporated in the unitwhereby air being compressed thereby can be utilized in associatedsystems as, for example, the air aspiration portion of a fuel supply fora gas turbine without worrying about dirt particles or the likeaffecting the operation of the associated systems.

To accomplish these desirable results, the cover plate 42 includes atubular extension 78 directed from the Wall 44 to define a large volumecavity 80 opened to the surrounding atmosphere. The tubular extensionhas a plurality of air cooling fins 82 formed on the outer peripherythereof formed more or less in axial alignment with the fins 26, 18 onthe pump cylinder 24 and base 16 of the compressor 10.

The cavity 80 has a planar extent substantially equal to the planarextent of the vertical cross sect-ion area through the pumping cylinder24. concentrically of the extension 78 is located a connection post 84that extends from the end Wall 44 substantially to the outer end of thetubular extension 78. Securedon the post 84 is a thin cover plate 86that completely overlies the opening into the cavity 80 except for alimited annular opening 88 formed continuously therearound defined, inpart, by the outermost end of the extension 78. The cover plate 86 andthe relatively large volume cavity 80 serve in cooperation toeffectively muflie mechanical noises directed therethrough from theoperative parts of the compressor 10. Furthermore, the cavity 80 andplate 86 serve as a housing for a large surface area annular filteringmember 90 having one end thereof supportingly received by a recess 92 onthe outer surface of the end wall 44 and the opposite end thereofengaging the inner surface of the cover plate 86 which is held tightlythereagainst by a screw element 94 directed therethrough into threadedengagement with the post 84.

By vintue of the aforementioned construction, air drawn through theannular opening 88 is cleaned by the filter member 90 prior to passageinto the inlet snout 76. An additional feature of the above-describedfilter and muflling assembly is that by the provision of the largevolume cavity and the inlet snout 76, the inlet air flow into thepumping cavity 28 is substantially evened out to reduce pulsating fluidnoise emanations from the unit 10.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight .be adopted.

What is claimed is as follows:

1. An air compressor comprising, an open-ended cylinder forming acavity, impeller means in said cavity including means for dividing saidcavity into a variable volume intake chamber and a variable volumedischarge chamber, an inlet and an outlet in communication with saidchambers, a base plate for closing one end of said cylinder, a coverplate for closing the other end of said cylinder having said inlettherein, said cover plate including an outwardly opened enclosure havinga planar extent substantially equal to the outer dimension of saidcylinder, an annular filter disposed within said enclosure surroundingsaid inlet opening in spaced relationship therewith, closure means forclosing one end of said annular filter including means for producing anannular inlet opening into said enclosure for directing fluid intakeacross said filter and thence through said inlet into said cavity, saidclosure means in cooperation with said enclosure forming .a large volumechamber serving to muffle noises within said cavity produced duringcompressor operation.

2. .An air compressor comprising, an open-ended cylinder forming acavity, impeller means in said cavity including means for dividing saidcavity into a variable volume intake chamber and a variable volumedischarge chamber, an inlet and outlet in communication with saidchambers, a base plate for closing one end of said cylinder, a coverplate for closing the other end of said cylinder having said inlettherein, said cover plate including an outwardly opened enclosure havinga planar extent substantially equal to the outer dimension of saidcylinder, an elongated tubular intake member directed into saidenclosure for communicating the interior of said closure with said inletopening, an annular filter disposed within said enclosure surroundingsaid tubular intake member in spaced relationship therewith, closuremeans for closing one end of said annular filter including means forproducing an annular inlet opening into said enclosure for directingfluid intake across said filter and thence through said tubular intakemember into said pumping cavity, said closure means in cooperation withsaid enclosure forming a large volume intake mufiling chamber which incooperation with said tubular intake member mufflles pulsating fluidintake noises in such structure, said mufiiing chamber and closure meansalso silencing mechanical noises during compressor operation.

3. In an air compressor, the combination of, a housing having an openend, means in said housing forming a cavity, impeller means in saidcavity including means for dividing said cavity into variable volumeinlet and discharge chambers, an inlet and an outlet communicating withsaid chambers, a cover plate for closing the open end of said housingincluding said inlet therein, said cover plate including an outwardlyopened enclosure, closure means for covering the opened end of saidenclosure to form a cavity having an annular inlet opening, an elongatedtubular intake member disposed within said enclosure cavity fordirecting fluid into said inlet opening, said enclosure cavity andtubular intake member serving to mutfle pulsating fluid flow producedsound waves.

4. In an air compressor, the combination of, a housing having an openend, means in said housing forming a cavity, impeller means in saidcavity including means for dividing said cavity into variable volumeinlet and discharge chambers, an inlet and an outlet communicating withsaid chambers, a cover plate for closing the open end of said housingincluding said inlet therein, said cover plate including an outwardlyopened enclosure, closure means for covering the opened end of saidenclosure to form a cavity therein having an annular inlet opening, anannular filter member disposed in said enclosure cavity having one endthereof in engagement with said cover plate and the opposite end thereofblocked by and in engagement with said closure means, an elongated"tubular intake member disposed within said filter IfOI directing fluidinto said inlet opening, said enclosure cavity and closure means servingto mufiie mechanical noise emanating from said air compress-or, saidenclosure cavity and tubular intake member serving to mufiie pulsatingfluid flow produced sound waves.

5. In an air compressor, the combination of, a housing having an openend, means in said housing forming a cavity, impeller means in saidcavity including means for dividing said cavity into variable volumeinlet and discharge chambers, an inlet and an outlet communicating Withsaid chambers, a cover plate for closing the open end of said housingincluding said inlet therein, said cover plate including an outwardlyopened enclosure, closure means for covering the opened end of saidenclosure including means for forming an annular inlet opening into theinterior of said enclosure, said closure means being spaced from saidpump housing a distance substantial air substantially equal to the depthof the cavity in said housing, an annular filter member disposed in saidenclosure having one end thereof in engagement With said cover plate andopposite end thereof blocked by and in engagement with said closuremeans, an elongated tubular intake member disposed within said filterfor directing fluid into said inlet opening, said enclosure forming aspace in cooperation with said closure means serving to mufflemechanical noise emanating from said air compressor, said enclosure andtubular intake member serving to mufiie pulsating fluid flow producedsound waves.

References Cited by the Examiner UNITED STATES PATENTS 2,096,891 10/1937Fredlund 230232 2,235,706 3/1941 Hanus 230-414 2,918,009 12/1959Crevoisier 230152 X ROBERT M. WALKER, Primary Examiner.

1. AN AIR COMPRESSOR COMPRISING, AN OPEN-ENDED CYLINDER FORMING ACAVITY, IMPELLER MEANS IN SAID CAVITY INCLUDING MEANS FOR DIVIDING SAIDCAVITY INTO A VARIABLE VOLUME INTAKE CHAMBER AND A VARIABLE VOLUMEDISCHARGE CHAMBER, AN INLET AND AN OUTLET IN COMMUNICATION WITH SAIDCHAMBERS, A BASE PLATE FOR CLOSING ONE END OF SAID CYLINDER, A COVERPLATE FOR CLOSING THE OTHER END OF SAID CYLINDER HAVING SAID INLETTHEREIN, SAID COVER PLATE INCLUDING AN OUTWARDLY OPENED ENCLOSURE HAVINGA PLANAR EXTENT SUBSTANTIALLY EQUAL TO THE OTHER DIMENSION OF SAIDCYLINDER, AN ANNULAR FILTER DISPOSED WITHIN SAID ENCLOSURE SURROUNDINGSAID INLET OPENING IN SPACED RELATIONSHIP THEREWITH, CLOSURE MEANS FORCLOSING ONE END OF SAID ANNULAR FILTER INCLUDING MEANS FOR PRODUCING ANANNULAR INLET OPENING INTO SAID ENCLOSURE FOR DIRECTING FLUID INTAKEACROSS SAID FILTER AND THENCE THROUGH SAID INLET INTO SAID CAVITY, SAIDENCLOSURE MEANS IN COOPERATION WITH SAID ENCLOSURE FORMING A LARGEVOLUME CHAMBER SERVING TO MUFFLE NOISES WITHIN SAID CAVITY PRODUCEDDURING TTHE COMPRESSOR OPERATION.